<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <!--viewport针对移动端开发的时候将页面调整为合适大小-->
    <title>Document</title>
    <style>
        div{
            width: 100px;
            height: 100px;
            background-color: red;
            background-color: blue;
        }
    </style><!--层叠样式表-->
</head>
<body>
    <div></div>
</body>
</html>